'Beep'. A woman straddles the retirement-aged man in the hospital bed, detaching his heart rate monitor. Metronomically counting the blips in order to effect a seamless switch, she is attempting to affix it to her own chest. 'Beep.' It's on. Having accomplished this task, she takes up the hypodermic with which she plans to liquidate her victim; with the monitor now returning a signal from a different pulse, the duty nurse in the adjacent staffroom will remain oblivious to her charge's plight.

As the syringe is tested, however, the man's eyes flick open. 'Beep?' he asks, with the tempered sarcasm of a bachelor uncle claiming an improbable PlayStation victory. James Gatehouse never misses a trick.

Stephen Rea's trilby-hatted sexagenarian, the antagonist of BBC2's The Shadow Line, lays claim to a presence which exceeds that of any British small-screen villain since Albie Kinsella, the skinhead spree killer Robert Carlyle played in Jimmy McGovern's Cracker. Aptly for a character belonging to a series so utterly unconvinced by the arguments of realism, Gatehouse is less a figure that we should be genuinely concerned about encountering in day-to-day life than a distillation of several ambiguously-charged images which have fretted at the collective unconscious for fifty or sixty years.

On one level, he's an inconspicuously remorseless gentleman spy of the le Carré vintage, but his threat also feeds considerably on Harold Pinter's origin-less inquisitors, Doctor Who's Master, and – implausible as it might sound for the principle adversary of a purportedly 'gritty' police drama – the medley of middle-class demonologists and suburban necromancers Hammer House of Horror brought garishly to life in the early 80s. With a pedigree of eeriness which leans so heavily on a bygone iconography of menace, Gatehouse may well represent primetime's hauntological turn.

Those who have tracked the shift towards the ghostly in British underground music over the last couple of years might feel that hauntology is due a critical exorcism by now. For the Thursday evening TV audience, however, it could still require some introduction. To recap, Simon Reynolds appropriated the neologism from the late work of post-structuralist philosopher Jacques Derrida in order to describe a musical aesthetic which manipulates old library recordings, obsolete electronics, static, and musique concrete's repertoire of techniques to produce disquieting, melancholy effects.

Where some genres – Britpop serves as straw man here – reach backwards in a nostalgic shirking of the responsibility to produce material which might challenge the listener, hauntology bends towards those instances belonging to the cultural past in which the weird and ambiguous were purposefully cultivated. It returns both to spurts of creativity which didn't find their way into the mainstream and, almost contradictorily, to works which attained so great a familiarity through their exposure to a mass audience that their experimental brio was overlooked.

Chronologically-speaking, the lodestone of hauntological thinking is a period which extends from the late 60s to roughly the time of the Miners' Strike. It makes a romantic overture to the cultural – and political – achievements of British social democracy, belying an increasingly widespread yearning for the straighter, and yet far stranger, era before Thatcher's demolition of the Post War consensus. Drawn to the minor-key traumas of the public information film – Gatehouse, come to think of it, isn't a million miles from the unforgettable Spirit of Dark and Lonely Water – as well as the sonic adventurousness of the BBC Radiophonic Workshop and audacious grands projets in social housing and town planning, hauntology asks what kinds of futures might have matured from such instances of technical, stylistic, and political innovation in public life.

The BBC figures prominently in the preoccupations of this disposition. What emerged from Television Centre and Broadcasting House under a succession of modernising Director-Generals in the 60s and 70s has lately come to emblematise how publicly-funded bodies were once able to broadcast work with intellectual clout equal to social democracy's egalitarian ambitions.

A slightly extreme example, perhaps, but one might illustrate what has been lost since then by pointing to a hefty sag in the cerebral pitch of the Corporation's art documentaries: where the 70s gave us the rigorous Marxian demystifications of John Berger's Ways of Seeing, the noughties serve up Andrew Graham-Dixon cooing over the rugs at Petworth. Adam Curtis might come along every couple of years to throw a little light on game theory or macroeconomics using nothing but old tourist promos and the shadier reaches of his iPod, but – due to deregulation - the state broadcaster has become palpably blunted by its subjection to market forces it hasn't always been required to appease.

Over the course of its seven-episode run, The Shadow Line evokes some of the alluring disorientations and assured intelligence of a prelapsarian BBC. Press coverage ahead of its release led many to expect a tea-and-toast spin on The Wire, but, from the Beckett-quiet mumblings, bruised palette, and explicit artificiality of the first episode's opening scenes, it's clear that writer-director Hugo Blick possesses inclinations substantially dissimilar to the American show's exhaustive realism. None of the characters, with the possible exception of Christopher Eccleston's flower importer-cum-smack wholesaler Joseph Bede, seem designed to be played naturalistically, permitting a staginess in which a thespy cast – Rea; Anthony Sher as errant drug financier Peter Glickman; Rafe Spall as the thuggish, deceptively guileless, Jay Wratten – could thrive.

On one level or another, every single scene inspires bewilderment on the viewer's part. An image from the fourth episode of Gatehouse sitting atop a filing cabinet whilst surveilling the offices of Glickman's son, for example, exudes poetic surreality in a manner we probably haven't been blessed with since Twin Peaks; Spall's wired, hyper-stylised delivery indicates a sensitivity for the surreptitious camp of criminality that the makers of more straight-laced cop shows seem determined to ignore.

Perhaps it's the script's cavalier attitude to sense-making, or its tonally-bumpy marriage of unforgiving noir and unexpected belly laughs, but critics were not uniform in their appreciation of The Shadow Line. With disheartening literal-mindedness, a number accused Blick's dialogue of being clichéd – more of which in a moment – and pilloried the plot as implausible and convoluted. These allegations miss the point: even repeated viewings won't discern that much logic in the story, which turns on institutional corruption, the mnemonic exertions and amorous subterfuges of DI Jonah Gabriel (Chiwetel Ejiofor), and something unintelligible about police pension schemes.

All of this is, in practice, an elephantine MacGuffin configured to take us from one set-piece to another and to justify increasingly outlandish onscreen interactions. That straightforwardness and plausibility of plot are now principle measure of a show's calibre – hence Channel 4's ironing out of some of the ambiguities of their adaptation of David Peace's Red Riding in 2009 – speaks volumes about a retreat from experimentalism in television drama; The Shadow Line seems to want to reverse this process and reclaim the medium for oddness once again.

So much of this is achieved through what the less charitable might deem to be directorial tics. One scene in which Gatehouse does for a meddling investigative journalist by running his motorcycle off the road exemplifies this: a combination of uncomfortably forced camera angles and over-extended shots – techniques which once again recall nothing so much as Hammer House of Horror at its most perverse – cultivates a sense that everything is slightly out of line with contemporary dramatic convention. This attention to visual detail, when compared to the vaguely slipshod approach of other recent conspiracy narratives such as Paul Abbott's Exile, marks The Shadow Line out as a counter-argument to the jadedness of so much of what the BBC has to offer these days.

Blick also capitalises on awkwardness and incongruity in his dialogue, having characters lengthily spin out laboured metaphors in a manner which, whilst read by some as an inability to make the show's language escape cliché, effectively depicted a world in which individuals lack the wherewithal to use words to control their own destinies. In the plays of Beckett and Pinter, cliché is what characters reach for when they're incapable of grasping the enormity of the situations which confront them: crime and corruption, The Shadow Line implies, have the power to overwhelm our linguistic capacities.

Amongst a huge cast, only Gatehouse regularly speaks without having recourse to cliché. As the half-seen controller of everything that is said and done in the show, he serves as a surrogate version of a director within the narrative. Considering this together with his distinctly anachronistic demeanour, it's tempting to think that his part is an allegorical one: it was, in a way, as if an old version of the BBC – a version in which wit and nuance won out over insistent, yet meaningless, valorisations of the 'new' – is picking off its progeny.

In its depiction of an environment in which almost nobody could manage to say anything constructive, The Shadow Line seems to be taking a pop at the vacuity of contemporary drama's rhetoric of earnestness by presenting the triumph of a character who is, in the final account, utterly unencumbered by emotional investments. Gatehouse's troubling affectlessness resurrects the ambiguous terrors of Cold War thrillers and paranoia-tinged curiosities such as The Prisoner; behind this, perhaps, lies a conviction that TV's real strength is its capacity to leave the viewer with unanswered questions. This is the BBC at the top of its game, in spite of the arguments of reviewers who tend to reserve their praise for what arrives here from the American networks, and it presents a timely case for state-subsidised complexity.

The Shadow Line is out now on 2 Entertain DVD